#include "math.h"

double exponential (double x, int n)
{
  if (n==0)
    return 1;

  return x * exponential (x, n-1);
}

int fac (int n)
{
  if (n==0)
    return 1;

  return n*fac(n-1);
}

double sin (double x)
{
  double result;

  result = x-(exponential(x, 3))/fac(3)+(exponential(x, 5))/fac(5);
  return result;
}
